Module part

ABSTRACT

A module component with a good shield effect and a low height including a circuit board having mounted thereon a mount device including an electronic part. The device is sealed with a sealing body having a metal film formed on the sealing body surface. A ground pattern is formed at the outer periphery of the principal surface of the circuit board. The metal film is conductively connected with the ground pattern.

TECHNICAL FIELD

The present invention relates to a module component used for variouselectronic devices, communication devices, etc.

BACKGROUND ART

Conventional module components are configured of a circuit board 21carrying one or more mount device 23 at least o one side thereof, aground electrode 24 provided on the side surface of the circuit board21, and a metal case 22 covering the mount devices 23. And, electricshield is achieved with a configuration in which one end of the metalcase 22 is connected with the ground electrode 24 by means of solder. Inorder for the metal case 22 to be connected with the side surface of thecircuit board 21 by means of solder as in the conventional modulecomponent described above, the thickness of the circuit board 21 isneeded to be large enough for the metal case 22 to be able of supportingitself. Moreover, if the mount device 23 carried by the circuit board 21comes in contact with the metal case 22, short circuit or disorders incircuit operation caused by external stress takes place. For theprevention of such troubles, the height of the metal case 22 needs bemade larger than the height of the mount devices 23. Furthermore, in theconnection of the circuit board 21 with the metal case 22, care is takenso that the metal case 22 never comes in contact with the circuitpattern and the mount devices 23 formed on the surface of the circuitboard 21. For that purpose, a clearance is provided between the circuitboard 21 and the metal case 22.

And, a terminal formed on the metal case 22 is connected with the groundelectrode 24. As the result of these measures, thinning of the componentis difficult, and the shield effect tends to be imperfect. In view ofthe problems mentioned above, the invention has an object of making amodule component low in height and achieving a sufficient shield effect.

DISCLOSURE OF THE INVENTION

A module component is provided comprising a circuit board carrying amount device comprising an electronic part, a sealing body that has thesame outer shape as that of the circuit board and seals the mount devicewith a first resin, and a metal film covering the surface of the sealingbody and the side surface of the circuit board, wherein a ground patternis formed at the outermost periphery of the uppermost layer surface ofthe circuit board and wherein the metal film and the side end portion ofthe ground pattern is conductively connected.

Moreover, a module component is provided comprising a circuit boardcarrying a mount device comprising an electronic part, a sealing bodythat has the same outer shape as that of the circuit board and seals themount device with a first resin, and a metal film covering the surfaceof the sealing body and the side surface of the circuit board, whereinthe sealing body has a dividing groove corresponding to a predeterminedcircuit block and in at least either of the bottom surface or the sidesurface of the dividing groove the metal film is connected with theground pattern of the circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a module component as a first embodimentof the invention.

FIG. 2 is a cross-sectional view of a module component as the firstembodiment of the invention at the section shown by line A–A′.

FIG. 3 is a cross-sectional view of a module component as anotherexample of the first embodiment of the invention.

FIG. 4 is a perspective view of a module component as a secondembodiment of the invention.

FIG. 5 is the cross-sectional view of a module component as the secondembodiment of the invention at the section shown by line A–A′.

FIG. 6 is a cross-sectional view of a module component as anotherexample of the second embodiment of the invention.

FIG. 7 is a perspective view of a conventional module component.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, embodiments of the invention are described withreference to the drawings.

By way of precaution, the drawings are schematic ones, and thus do notshow individual positions in a dimensionally correct form.

(First Embodiment)

By using FIGS. 1 and 2, the module component in the first embodiment ofthe invention is described. The circuit board 10 is configured of amulti-layer substrate.

In this multi-layer substrate, circuit patterns such as those for apower supply, ground, high frequency, etc. are fabricated in at leasttwo wiring layers.

On the principal surface of this circuit board 10, mount devices 30 suchas a resistor, a capacitor, a coil, a semiconductor, a quartzoscillator, etc. are mounted. The connection among them is achieved byusing a lead-free solder. Furthermore, such connection may be achievedby means of an electro-conductive adhesive. Publicly knownelectro-conductive adhesives can be used. At the rear surface of thecircuit board 10, an electrode 11 is provided which is to be connectedwith a mother board (not shown in the drawing). And, a sealing body 40made of an epoxy-based resin as a first resin is configured so as tocover these mount devices 30 to have the same outer shape as that of thecircuit board 10. Further, on the surface of this sealing body 40 andthe side surface of the circuit board 10, a metal film 20 is formed.This metal film 20 is connected with a first ground pattern 50 formed onthe four sides of the outermost periphery in the principal surface ofthe circuit board 10. With such a configuration, the circuit board 10 iscovered with the metal film 20 except for the electrode 11 on the rearsurface thereof. As a result, a reliable shield effect is attained. Asis shown in FIG. 2, it is possible to connect a ground pattern 50 formedon the principal surface of the circuit board 10 with the metal film 20.Moreover, as is shown in FIG. 3, it is further possible to connect theside end of the ground pattern 12 formed in the outer periphery of therear surface of the circuit board 10 with the metal film 20. And, whenthe thickness of the metal film 20 is about 1 μm or more, a sufficientshield effect is attained. This metal film 20 can be fabricated by firstforming a layer made of copper and the like by means of electrolessplating on the surface of the sealing body 40, and then further coveringits surface with an electroplated layer. By such procedure, the metalfilm 20 is made dense and close. As a result, the contact resistancewith the ground pattern 50 can be made low, thus improving the shieldeffect since the ground potential of the metal film 20 formed on thesealing body 40 is stabilized.

As are shown in FIGS. 2 and 3, a configuration is adopted in which theprojected area of the sealing body 40 covered with the metal film 20 isequal to the projected area of the circuit board 10.

Since there is no bump between the sealing body 40 and the circuit board10, it becomes possible to uniformly achieve an intimate contact of themetal film 20 formed by electroless plating together withelectroplating. As a result, the peeling off of the sealing body 40 andthe ground pattern 50 can be prevented. In this way, the ground pattern50 formed on the circuit board 10 and the metal film 20 formed on thesealing body 40 are connected together. And, it becomes possible toreliably shield the circuit comprising the mount devices 30 provided onthe circuit board 10.

(Second Embodiment)

Among the module component in the second embodiment, the sameconstituents as in the first embodiment are described with the samesigns.

As is shown in FIG. 4, the sealing body 40 covered with the metal film20 is divided into three blocks by means of a sealing body 70 made of asecond resin. In the circuit board 10, as is shown in FIG. 5, circuitpatterns such as those for a power supply, ground or high frequency,which have been described in the first embodiment are provided in atleast two wiring layers. In the outer periphery of the principal surfaceof the circuit board 10 is formed a first ground pattern 50. Further, onthe principal surface of the circuit board 10, the mount devices 30 suchas a resistor, a capacitor, a coil, a semiconductor, a quartz oscillatorand the like are mounted. And the sealing body 40 having the same outershape as that of the circuit board 10 is provided so as to cover thesemount devices 30. Still further, a dividing groove 60 is provided in thesealing body 40 for the purpose of dividing the component intopredetermined circuit blocks.

On the surface of the sealing body 40 as well as the dividing groove 60,the metal film 20 is formed in such a manner as to be connected with thesurface of the ground pattern 50.

Moreover, the sealing body 70 made of the second resin is provided onthe metal film 20 formed in the dividing groove 60.

As has been stated hereinabove, the dividing groove 60 that dividesmount devices 30 into predetermined circuit blocks is provided, and thenthose blocks are covered with the sealing body 40. On the surface ofeach circuit block, the metal film 20 is provided so as to be inconnection with the first ground pattern 50. In this way, eachpredetermined circuit block is electrically shielded from each other. Asa result, the module component can be configured small in size, becausethere is no interference of electric noise among the module componentseach having a plurality of circuit blocks. Further, the sealing body 70made of the second resin is formed in the dividing groove 60. As aresult, even with a small thickness resulting from height reduction, themodule component has a sufficient bending strength and can maintain itsdeformation small. And, since the reliability in the contact between themetal film 20 and the ground pattern 50 is secured, shieldingperformance is also enhanced. FIG. 6 illustrates an example in which themetal film 20 is configured so as to be in connection with the groundpattern formed within the circuit board 10. In such a case, it becomespossible to shield part of the circuit pattern formed within the circuitboard 10. As a result, the shield effect is still further enhancedcompared with the example illustrated in FIG. 5.

In addition, a sealing body 13 made of a third resin is arranged in theclearance between the circuit board 10 and the mount devices 30comprising electronic parts. In this way, the air present in theaforementioned clearance is excluded, thus enabling further enhancementof reliability.

Incidentally, the sealing bodies each made of the first, second or thirdresin may be the same or different. As the composition thereof, inaddition to epoxy-based resins, insulating resin compositionsincorporated with a variety of inorganic fillers can be used. Thoseresin compositions that have a good heat-resistance and a good thermalconductivity are particularly preferred. As an example, the compositioncomprising a silicone resin containing alumina particles can bementioned.

INDUSTRIAL APPLICABILITY

As has been explained hereinabove, a module component is provided havinga configuration which carries, on a circuit board, a mount devicecomprising an electronic part, and has a sealing body that seals themount device with a resin and a metal film covering the surface of thesealing body, wherein a ground pattern is formed at the outer peripheryof the principal surface of the circuit board and wherein the metal filmand the ground pattern are conductively connected.

With such a configuration, one can provide a module component that hasan enhanced shield effect and can be made small in size.

1. A module component comprising: a circuit board carrying a mountdevice comprising an electronic part, a sealing body that has the sameouter shape as the outer shape of the circuit board and seals said mountdevice with a first resin, and a metal film covering the surface of thesealing body and the side surface of the circuit board, wherein (1) thesealing body has a dividing groove corresponding to a predeterminedcircuit block, (2) the dividing groove is sealed with a second resin,and (3) the metal film is connected to the ground pattern of the circuitboard in at least one of a bottom surface of the dividing groove and aside surface of the dividing groove.
 2. The module component of claim 1,wherein (1) the sealing body has a dividing groove corresponding to thepredetermined circuit block, and (2) the circuit block is electricallyshielded from another circuit block.
 3. The module component in claim 1wherein the metal film has a configuration prepared by first forming alayer by means of electroless plating and then forming an electroplatedlayer on the layer formed by electroless plating.